The HBO series aired in March and April. It stars Paul Giamatti and Laura Linney, and is based on David McCullough’s best-selling, Pulitzer Prize-winning biography, which gave the park attendance an even bigger boost when it was published in 2001.

Last year the park had 227,000, three times the total of the years before McCullough’s book revived the second president’s stature and put the Quincy park on the national map.

Keinath said the “HBO effect” is also significant because it’s bringing a different group of visitors – viewers, rather than book readers and history buffs.

This is posing a challenge to the park, though it’s one any site would welcome: Larger crowds are forcing the Adams Park to come up with new ways to provide a complete visit for everyone.

The park has doubled its staff of rangers and guides, from 10 to 20, and is planning to conduct more extensive trolley tours in July and August.

The tours are partly aimed at easing the demand for tours of the Old House, the park’s key site, where John and Abigail Adams, their son and president John Quincy Adams and two other generations of the family lived.

With a limit of 10 people per tour in an 18th century house, “that’s a significant challenge,” Keinath said. “We want everyone who comes to have a good experience.”